Means for producing special cams



Jan. 30, 1962 H. A. GEORGE MEANS FOR PRODUCING SPECIAL CAMS Original Filed March 31, 1954 INVENTOR Ho WflPD A. GJE'ORGE ATTORNEY 1 Claim. (CI. 90-15) This invention relates to machine means for making specially shaped cams.

This application is a division of co-pending application, Serial No. 420,031, March 31, 1954, now abandoned entitled Adjustable Cam Means for Winding Machines.

More particularly the invention relates to means for producing cams for winding special electrical coils. The special electrical requirements of these coils with respect to distributed capacity require certain configurations which may be produced by controlling the winding machine with specially shaped cams. A typical cam is one having a heart shaped face at one end and a circular face at the other end, and being smoothly connected in between. Since these cams are used for the very accurate placement of wires on a coil, they must be very accurately made. However, due to the irregular shape, it is impossible to produce these cams with conventional machines. The present invention provides means to make such cams with accuracy. I

The adjustable cams made by the present invention provide means for adjusting and modifying the throw of the cam without changing cams, and even for making fine adjustments while the machine is running. This reduces set-up time tremendously and provides products which could not be made with standard size cams.

Accordingly, a principal object of the present invention is to provide new and improved adjustable cam making means. v

Another object of the present invention is to provide new and improved means for making adjustable cams for coil winding machines.

Another object of the present invention is to provide new and improved means for making cams having a smoothly adjustable throw, thereby eliminating the need for a multiplicity of different cam sizes or shapes.

Another object of the present invention is to provide new and improved three dimensional adjustable cam means.

Another object of the present invention is to provide means for making cams of the type having one heart shaped face for one cam throw, the other face being a heart shaped face having a smaller throw or a circle having zero throw, and being smoothly tapered between faces.

These and other objects of the invention will be apparent from the following specification and drawings, of which:

FIGURE 1 is a perspective view of heart shaped cam.

FIGURE 2 is a perspective view of a cam formed in accordance with the means of the present invention.

FIGURE 3 is a plan view of the cam shown in the embodiment of FIGURE 2.

FIGURES 4 and S are sectional views of the cam shown in FIGURE 3.

FIGURE 6 is a side view of the cam shown in FIG- URE 3.

FIGURE 7 is a plan view of an embodiment of the invention for generating or manufacturing special cams, and

FIGURES 8 and 9 are other cams which may be made by the means of the present invention.

FIGURE 1 illustrates a conventional heart shaped earn a conventional it; ted States Pate While all 3,018,695 Patented Jan. 30, 1962 1 commonly employed in some coil winding mechanisms. A .cam with a constant displacement for each degree of rotation is shown since this is the most used motion. The symmetrical design provides for a linear traverse in 180 of rotation and a traverse, also linear, in the opposite direction for the remaining 180. It should be noted that the shape of follower 9 mechanism, affects the linearity of the resultant motion. This is shown by the dotted line 8 which traces the path of the follower as the cam rotates. The path is shown to meet the above conditions although the surface on the cam would not.

The eifective throw of the cam in FIGURE 1 is the difference between the minimum and maximum dimensions of the cam, that is, B-A.

FIGURE 2 shows an embodiment of a cam of the present invention. It is heart shaped at one end 2 to provide a. throw B-A as in FIGURE 1. It is circular at the other end 3 which provides zero throw since A=B. Between the two ends it is smoothly tapering. Intermediate sections like 4 are heart shaped and have a corresponding intermediate throw. For instance, if the heart face 2 has a throw of .250" and the circular end 3 has a throw of .000", then all throws between these limits are obtainable by moving the cam along its axis. Intermediate throws differ in size but not in characteristic shape.

In FIGURE 3 the X axis is constructed so as to pass through the minimum and maximum dimensions of the heart face of the cam which are 180 apart by definition. The Y axis is originally placed at a position to the X axis, so as to intersect the X axis at the center of rotation of the cam. By previous definition it should be noted that A+B=A'+B'. It should also be noted that with the Y axis in the 90 position A=B. If the Y axis is rotated clockwise so that it approaches X axis, A will decrease uniformly with rotation until it equals A, while B will increase accordingly to B, the fundamental relationships mentioned above remaining, that is,

of this discussion could properly have been a simple cam as in FIGURE 1, the subject cam is a three dimensional concept which meets these requirements at any plane perpendicular to its axis. It should be further stated that a section through the cam parallel to its axis on the line X--X' will show a section which is a parallelogram as in FIGURE 5, while a section taken through the axis YY' is a rectangle as in FIGURE 4. Any section taken on the line Y-Y as it rotates toward XX' is a transition from the rectangle to the parallelogram in which the angle 0, FIGURE 5, is constantly becoming more acute. FIGURE 6 is a left side view of FIGURE 3.

Another method of defining the shape of this cam may be by means of discussing its method of generation. In FIGURE 7, the cam 10 is mounted on a spindle 11 such as in a lathe 19. A motor driven cutting tool such as an end-mill 12 is mounted on a rotating table 13, the rotation of this table being geared in predetermined relation to the spindle on which the cam is mounted through suitable worm 14, spur 15 gearing and change gears 11'. The solid lines show the position of the rotating end-mill 12 at the 90 or mid point of the generating motion, while the upper and lower dotted positions show the location of the end-mill at the minimum and maximum traverse of the generated cam. Suitable change gears 11 are used to achieve the desired traverse in of cam generation. It should be noted that the end-mill 12 which generates the surface of the cam is preferably of the same radius as the cam follower to be used. The center of the end-mill traverses a path indicated by the dotted line applied to 8, in FIGURE 1, while the cutting edge of the end-mill fol-lows the desired contour. To produce cams of maximum accuracy, the spindle 11 holding the cam 10 and the axis of the cutter 12 must not only be parallel at the 90 point, but must lie in the same plane at all times.

If the center of rotation 13 of the table 13 on which the cutting tool is attached coincides with the plane of either face of the cam as shown in FIGURE 7, then that face is circular and has a zero throw. If this pivot point falls between the two faces of the cam, then the resulting unit has a or null point at a corresponding plane. On each side of this point lie planes which produce throws equal but opposite to each other and progressively larger. If the pivot point falls outside of the cam, then no Zero throw exists and the resulting cam provides adjustment between the limits available at each heart shaped face. The cam may be set on the spindle as desired with respect to the plane of the center of rotation of the rotatable table.

Cams of this type may not be made with conventional apparatus since it is necessary that a rotation cutter be geared to a work turning device in a predetermined man ner. Other methods of making the cams such a planing are not practical as the desired turning relationships could not be obtained.

A cam such as shown in FIGURE 8 has a uniform rise in one direction and a virtually instantaneous drop-01f for return. One face 30 is a circle and the other face 31 is a helix, and the cam smoothly connects the two faces. Such a design is particularly useful for winding the pattern generally referred to as bank windin Such a cam, of course, is generated in a single pass in which the blank that is being rnilled is rotated 360.

Referring to FIGURE 9 we have generated a cam which is no longer heart-shaped but which has very desirable characteristics for winding superior progressive universal coils and so-called progressive bobbins. This cam has a throw which is the same throughout its length of adjustment, but the characteristics of that throw or traverse are adjusted within the limits set by the characteristics of each face. The practical application is one in which one face 32 has the point of the heart located 180 from the notch while the opposite face 42 has the point located 90 from the notch. This provides equal velocities in both directions on the one face and dillenng velocities elsewhere on the cam, the relative rate or difference between the two directions being adjusted by means of moving the cam between the followers. To generate such a cam it is necessary that the change gears 11 be chosen differently for cutting the rise of the cam from those used for cutting the return.

Therefore, our entire attention concerns cams and the means of fabricating them in which the throw and/or any other desirable characteristic can be adjusted by bringing the desired area of the cam surface into play. Such cams may be thong t of as the blending together of the areas between the two faces each of which represents some kind of limit of requirement, such as maximum and minimum throw, so that one can be certain that the desired characteristic can be found by merely selecting the proper point on the cam. The blending mentioned above is accomplished by the use of the rotary table for the support of the milling cutter of the subject application.

I claim:

Means for making, independently of other cams or templates, a cam having a heart shaped cross-section at one end and a circular cross-section at the other end comprising, a rotatably mounted spindle adapted to rotate a cam blank, a motor driven cutting tool mounted on a rotatable table, the normal position of said cutter being parallel to said spindle, the center of rotation of said table being in the plane of one face of said cam blank, and gear means directly connecting said table, and said spindle comprising a wonn gear connected to rotate said table, and a pair of meshing gears connecting said spindle and said worm gear.

References Cited in the file of this patent UNITED STATES PATENTS 1,629,910 Fleitcr May 24, 1927 1,656,598 Merrifield Jan. 17, 1928 1,689,370 Tessky Oct. 30, 1928 2,366,993 Antos Jan. 9, 1945 2,423,941 Laisne July 15, 1947 2,572,395 Savage Oct. 23, 1951 2,773,432 De Vlieg Dec. 11, 1956 2,784,649 Von Zelewsky Mar. 12, 1957 FOREIGN PATENTS 245,668 Great Britain Jan. 14, 1926 

